Chain saw



FIG. 1 is a front view of a chain saw showing our design;

FIG. 2 is a rear view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side View thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a top front perspective view thereof; and,

FIG. 8 is a bottom rear perspective view thereof.

The broken lines in the drawings illustrate portions of the chain saw and form no part of the claimed design. 

CLAIM The ornamental design for a chain saw, as shown and described. 